National Wind Watch: Wind Energy News » Turbine infrasound sounds familiar

The infrasound, a low noise level barely audible to human hearing, from wind turbines doesn’t appear to pose a risk to people, said an engineering expert during an environmental review tribunal hearing in Chatham Wednesday.

“The infrasound from wind turbines is not markedly different from ambient infrasound from other sources,” said Brian Howe, an engineer from HGC engineering, called as an expert witness for the Ministry of the Environment.

Noting people are continually surrounded by infrasound from a variety of sources in daily life, Howe said, “it’s pretty clear there’s no widespread health issues from ambient infrasound.”

Howe is one of two engineers who appeared at the hearing into a challenge by Katie Erickson and Chatham-Kent Wind Action Inc. to a renewable energy project approval given to Suncor Energy, the principal owner of the Kent Breeze Wind Farm, under construction near Thamesville. The project is the first to be approved under the Ontario Green Energy Act.

Howe said concerns about infrasound didn’t arise until humans began travelling into space. But, concerns surrounding infrasound don’t arise until the levels “reach an extremely high level,” he added.

However, Howe said low-frequency sound from mechanical tones, such as the gear box of a turbine, can be detected inside a house, noting a window could amplify the sound at low frequency.

He said if complaints are made about sounds heard indoors, they should be taken seriously.

Howe authored a study for the Canadian Wind Energy Association in February 2007, titled, Wind Turbines and Sound: Review and Best Practices Guidelines.

Although much research has taken place since surrounding noise from wind turbines, Howe said his opinion with respect to infrasound coming from wind turbines hasn’t changed markedly.

However, he offers some other guidelines outside the engineering realm in the best practices guidelines, such as having a good public relations strategy, which includes communicating honestly with the community to educate them about such things as infrasound.

He added the public relations plan should extend beyond just getting the project built.

Howe said it is important for a project developer to maintain the turbines and respond to concerns quickly if a malfunction is causing it to make more noise than normal.

Payam Najafi-Ashtiani, an engineer with the consulting firm Aercoustics Engineering Ltd., was qualified as having expertise in acoustical engineering by the tribunal.

Eric Gillespie, lawyer for the appellants, asked Najafi- Ashtiani as an acoustician, does he agree wind shear will increase the sound level.

Najafi-Ashtiani said wind shear would increase the sound at the hub height of the wind turbine, but the ambient sound at the ground level would mask some of the increased sound.

When it comes to measuring sound from wind turbines, Najafi-Ashtiani said it requires a high degree of expertise to do an analysis of the data, quality equipment and an understanding of the limitation of the equipment.

“Anyone can go buy a noise level meter from Radio Shack,” he said, adding they won’t get accurate results.

Najafi-Ashtiani said the situation changes so much while taking sound measurements that an expertise in analysing the data is needed to get proper results.

“There’s variability in nature,” he said. “The analysis has to take into account that variability.”

The final witness is expected to be called Thursday. The hearing is held in council chambers at the Chatham-Kent Civic Centre, beginning at 10 a.m.